Airway Management Flashcards
What is the acceptable extubation failure rate?
10-20%
An re-intubation rate < 10 may indicate too conservative as approach
A re-intubation rate > 20 may indicate premature extubations
What are the criteria for weaning and extubating a patient?
A - patent. If in doubt check for cuff leak or look down.
B - minimal oxygenation supporr FiO2 < 0.4, PEEP < 8, adequate ventilatory drive, ability to clear secretions
C - haemodynamic stability
D - sufficient consciousness to protect airway
E - original pathology resolved, no impending procedures under GA/sedation
What factors suggest failure of a spontaneous breathing trial?
Physiological Hr > 20% increase or > 140 SBP > 20% baseline or >180/<90 Cardiac arrhythmias Resp rate > 50% BASELINE OR > 35 pAo2 < 8 ON fIo2 >0.5 pAco2 >6.5 pH < 7.32 Clinical Agitation or anxiety Depressed mental state Sweating/cyanosis Increased resp effort
What are the risk factors for failing extubation?
Age > 65 Underlying chronic cardiorespiratory disease Heart failure / LV dysfunction COPD OSA/obesity PaCO2 > 6.5 Neuromuscular disorders Positive fluid balance Ventilation > 6 days
How many ICU patients experience post extubation stridor? What are the risk factors?
16% Female Muscle weakness Tracheal infection TRacheal stenosis Recent airway surgery Intubation > 36 hours Excessive cuff pressures Large ETT Aggressive suctioning NGT insertion
What are the indications for tracheostomy in ICU patients?
Inability to maintain upper airway - primary pathology or neurological impairment
Prolonged ventolator wean
Inability to adequately clear secretions
What are the potential advantages of trache over ETT?
Shorter tube - reduced dead space, reduced resistance to gas flow, reduced work of breathing, easier access for suctioning
Reduced need for sedation - improved cough and secretion clearance, improved communication, better compliance with physio
Avoidance of ETT - better mouth care, potential for speech, potential to eat
What are the contra-indications for tracheostomy?
Local - anatomical abnormalities, infection over insertion site, known or suspected difficult ETT, short neck, obesity, unstable spinal injury
Systemic - coagulopathy, significant haemodynamic instbaility, significant resp support (FiO2 >0.6, PEEP >10), inability to tolerate changes in PaCO2 (e.g. raised ICP)
What are the complications of a tracheostomy?
Immediate - hypoxia, hypercarbia, loss of airway, aspiration, haemorrhage, damage to local structures, anaesthesia related e.g. anaphylaxis, hypotension
Early - infection, displacement with loss of airway, occlusion, tracheal injury, haemorrhage (mucosal injury or erosion into right brachiocephalic artery)
Late - tracheal dilatation, tracheomalacia, tracheal stenosis
What are the indications for bronchoscopy?
Diagnostic - broncho-alveolar lavage, biopsy, assessment of inhalational injury, confirm ETT position
Therapeutic- removal of bronchial obstruction, placement of bronchial stent
Assist invervention - FOI, perc trache, DLT insertion, positioning of endobronchial blocker
What is ARDS?
An inflammatory process affecting the lungs
Initial injury precipitates a sequence of events manifesting as impaired oxygenation, impaired compliance and increased dead space
It has 3 phases - exudative, proliferative, and fibrosing
What is the definition of ARDS?
Defined by the Berlin criteria
Timing - Occurs within 1 week of a known clinical insult
Chest imaging - bilateral opacities on CXR
Origin of oedema - resp failure not fully explained by cardiac failure or fluid overload
Moderate-to-severe hypoxia - defined by the PaO2/FiO2 ratio on a ventilator with >5cmh2o PEEP.
p:f < 39.9 > 26.6 = mild
p:f < 26.6 > 13.3 = moderate
p:f < 13.3 = severe
What is the differential diagnosis of ARDS?
Cardiogenic pulmonary oedema
Acute eosinophilic pneuimonia
Cryptogenic organizing pneumonia
Diffuse alveolar haemorrhage
What is the aetiology of ARDS?
Direct - pnuemonia, viral pnuemonitis, chemical pnuemonitis, smoke inhalation, near drowning, pulmonary contusions, reperfusion injury, thoracic radiation
Indirect - systemic sepsis, major trauma, pancreatitis, pregnancy-related, TRALI, tumour lysis syndrome
What are the general management strategies for ARDS?
Sedation - improves mechanical ventilation compliance and decreases O2 consumption
Neuromuscular blockade -improves compliance and decreases O2 consumption - not without complication - but there is evidence that they may decrease mortality if used early on in severe ARDS
Fluid balance - conservative strategy leads to improved lung function and reduced number of days on the ventilator but no decrease in mortality
House-keeping - infection control, DVT prophylaxis, Ulcer prophylaxis and nutrition
What ventilator strategies should be employed in ARDS?
Low tidal volume 6ml/kg, significantly decreases mortality vs 12ml/kg
Maintain plateau pressure < 30cnH2O
High PEEP - decreasing atelectotrauma - may improve mortality in those with severe ARDS
Recruitment maneauvres - no evidence to show improved outcomes
Permissive hypercapnia - acceptance of increased co2 and acidosis
Discuss the role of steroids in ARDS
Theoretically beneficial given inflammatory nature
Appear to increase oxygenation and number of ventilator free days
Given between days 7-13 may be associate with improved mortality, however late may increase mortality
Discuss the role of beta agonists in ARDS
Reduce extravascular lung water
No evidence on improved outcomes
What is the role of statins in ARDS?
Small study showed improvement in non-pulmonary organ dysfunction, larger study showed no benefit
What is the role of nitric oxide in ARDS?
Inhaled NO selectively vasoldilates those pulmonary vessels serving ventilated lung. Improves oxygenation but no evidence for improved outcomes
What are the mechanisms of inhalational injury?
Heat - causes oedema, eryhtema, and mucosal ulceration
Toxins- sulphur dioxide, chlorine, ammonia
Environmental hypoxia due to oxygen consumption
What is the pahophysiology pf inhalational injury?
Exudative phase - characterised by neutrophil influx, macrophage activation, increased permeability, type 2 pneumocyte dysfucntion and decreased surfactant production
Fibrotic phase - fibrosing alveolitis, neoangiogenesis collagen deposition
What signs are associated with airway burns?
Facial or muscoal burns, singeing of nasal hair, hoarse voice, carbonaceous sputum
What effect does carbon monoxide have?
Binds to Hb with 250 times the affinity of oxygen
Causes left shift of OHDC
Cellular cytochrome oxidase system is inhibited
Results in tissue hypoxia
